1. Field of the Invention
The present invention relates to a seat belt system equipped with a pretensioner for use with a seat belt retractor in a vehicle, etc. which forces a take-up spindle of a webbing to rotate when abrupt deceleration occurs on a vehicle, tensioning the webbing in an occupant restraint direction.
2. Description of the Related Art
In this type of retractor pretensioner, various types have heretofore known in view of the principle of an emergency webbing-winding structure. Such pretensionere include those of the type that a rotary element (mass element) is pushed by a gas pressure, the type of a so-called xe2x80x9cwell-bucketxe2x80x9d using a wire rope, the type that a spiral spring like member is caused to rotate by a gas pressure, and the type that the planet gears are caused to revolve and drive by a gas pressure.
In such pretensioners, those of the type that a rotary element is pushed by a gas pressure as disclosed in U.S. Pat. No. 4,444,010, DE-A1-195 12 660, DE-A1-196 02 549, etc. are known.
These pretensioners including rotary elements are represented by, for example, U.S. Pat. No. 4,444,010, in which high pressure gas causes multiple rotary elements to be press-delivered in a duct in the event of a vehicular collision, and these rotary elements are in turn engaged with drive gears arranged on the periphery of a retractor shaft, thus providing a torque of abruptly winding around a seat belt on the retractor shaft.
The above-stated pretension adapted to directly rotate the retractor shaft with biasing force of the rotary elements requires a long stroke for moving the rotary elements, or a long moving passage for the rotary elements, to generate sufficient biasing force. Such a long moving passage constructed linearly will bring a pretensioner as a whole to be large-sized in the particular direction. Hence, typically, much effort is made to ensure a sufficiently long stroke by meandering or spirally bending the pipe or the moving passage.
However, the pretensioner that ensures the aforementioned moving passage requires the pipe complicatedly bent, thus providing complexity in a machining process of the same with much requirement of improved machining accuracy such that a predetermined value of the passage width should be kept even at a curved portion. This leads to increased production costs while the pretensioner is inevitably increased in overall size owing to an increased volume though it may be possible to avoid a size increase of the pretensioner in a particular direction. Furthermore, complexity in moving passage conFIGuration still requires higher level measures against gas leakage. This finally brings increased production costs as well as an increase in size.
In order to overcome the foregoing disadvantages, an object of the present invention is to generate a sufficient amount of rotating a retractor shaft to wind up a webbing with a short moving stroke of a pressure transmission member that is pushed by a pressure to thereby attain a webbing-winding feature equivalent to an employment of a longer stoke. The present invention is also intended to downsize and simplify the entire structure to facilitate the vehicle-loading with low production costs.
It is another object of the present invention to reduce gas leakage within the moving passage.
In order to achieve the foregoing objects, the present invention provides a seat belt system equipped with a retractor including a pretensioner, the retractor comprising:
a retractor base;
a retractor shaft rotatably supported by the retractor base and biased in a webbing-winding direction;
a gas generator mounted to the retractor base;
a drive member driven by the gas generator to wind in the retractor shaft in the webbing-winding direction; and
a clutch mechanism connecting the drive member to the retractor shaft, the clutch mechanism comprising
a pulley connected to the drive member and coaxially aligned with the retractor shaft, the pulley having a cam, and
a plate rotatable relative to the pulley in a direction of rotation of the retractor shaft, the plate having integrally engaging fingers deformable to engage with the retractor shaft through the cam as the plate rotates relative to the pulley.
With the thus constructed system, the number of parts in the clutch mechanism can be reduced with low production costs.
In order to achieve the foregoing objects, the present invention further provides a seat belt system equipped with a retractor including a pretensioner, the retractor comprising:
a retractor base;
a retractor shaft rotatably supported by the retractor base and biased in a webbing-winding direction;
a casing mounted on the retractor base, including a pressure chamber and a moving element passage communicated to the pressure chamber;
a gas generator for generating a high pressure gas into the pressure chamber;
a drive member driven by the gas generator to wind in the retractor shaft in the webbing-winding direction; and
a clutch mechanism connecting the drive member to the retractor shaft,
wherein the drive member comprises:
a medium connected with the clutch mechanism; and
a moving member operable to actuate the medium and movable within the moving element passage, the moving element passage having a portion rectangular in transverse section relative to a moving direction of the moving member.
With the thus constructed system, the dimension widthwise of the retractor (the dimension as viewed longitudinally of the retractor shaft) can be reduced to downsize the retractor as a whole.
In order to achieve the foregoing objects, the present invention still further provides a seat belt system equipped with a retractor including a pretensioner, the retractor comprising:
a retractor base;
a retractor shaft rotatably supported by the retractor base and biased in a webbing-winding direction;
a gas generator mounted to the retractor base;
a drive member driven by the gas generator to wind in the retractor shaft in the webbing-winding direction;
a clutch mechanism connecting the drive member to the retractor shaft; and
a drive member releasing mechanism for, when the drive member further mover to a webbing winding-out position at the side of a webbing winding-out direction from the initial position before the gas generator is actuated, permitting the retractor shaft to rotate in a webbing winding-out direction in response to the movement to the winding-out position.
With the thus constructed system, the retractor shaft may be freely rotatable when the retractor shaft is wound out to the webbing winding-out position after the pretensioner has been actuated.
In order to achieve the foregoing objects, the present invention still further provides a seat belt system equipped with a retractor including a pretensioner, the retractor comprising:
a retractor base;
a retractor shaft rotatably supported by the retractor base and biased in a webbing-winding direction;
a gas generator;
a pipe-shaped member mounted on the retractor base, the pipe-shaped member including a circle-in-section part for receiving a gas pressure generated by the gas generator, and a rectangle-in-section part;
a drive member driven by a gas pressure generated by the gas generator to wind in the retractor shaft in the webbing-winding direction, the drive member comprising a medium and a moving member operable to actuate the medium and movable within the rectangle-in-section part of the pipe-shaped member; and a clutch mechanism connecting the drive member to the retractor shaft.
With the thus constructed system, the dimension widthwise of the retractor corresponding to the region where the moving member is movable can be reduced with the simplified structure.
In order to achieve the foregoing objects, the present invention still further provides a seat belt system equipped with a retractor including a pretensioner, the retractor comprising:
a retractor base;
a retractor shaft rotatably supported by the retractor base and biased in a webbing-winding direction;
a casing mounted on the retractor base, including a pressure chamber and a moving element passage communicated to the pressure chamber;
a gas generator for generating a high pressure gas into the pressure chamber;
a drive member driven by the gas generator to wind in the retractor shaft in the webbing-winding direction; and
a clutch mechanism connecting the drive member to the retractor shaft, and
wherein the drive member comprises;
a pushing member driven by a gas pressure generated by the gas generator and disposed in the moving element passage;
a tension member having one end mounted on the retractor base and the other end mounted on the clutch mechanism; and
a moving element pushed by the pushing member to press a portion between both ends of the tension member.
With the thus constructed system, a larger amount of the tension member can be wound out (increased speed) than a moving distance of the moving element, resulting in a compact pretensioner. Further, since the tension member that is retained by a clamp is released after the pretensioner has been actuated, the retractor shaft may be freely rotatable, making it possible to wind out the wound webbing.
In addition, the gas pressure can be effectively used with avoidance of any gas leakage from the moving element passage.